NATURAL SELECTION 69 



In the beginning of his fourth chapter (Origin 

 of Species), Darwin, after remarking that man in his 

 domestic productions cannot originate varieties, but 

 can only preserve and accumulate such as do occur, 

 says : " Unintentionally he exposes organic beings 

 to new and changing conditions of life, and variability 

 ensues : but similar changes of conditions might and 

 do occur under Nature. Let it be borne in mind, 

 how infinitely complex and close-fitting are the mutual 

 relations of all organic beings to each other, and to 

 their physical conditions of life : and consequently 

 what infinitely varied diversities of structure might 

 be of use to each being under changing conditions of 

 life. Can it be thought improbable, seeing that 

 variations useful to man have undoubtedly occurred, 

 that other variations useful, in some way, to each 

 being in the great and complex battle of life should 

 occur in the course of many successive generations ? 

 If such do occur, can we doubt (remembering that 

 many more individuals are born than can possibly 

 survive) that individuals having any advantage, how- 

 ever slight, over others, would have the best chance 

 of surviving and procreating their kind ? " 



It may not be thought improbable, as an a priori 

 concept, that in the course of many successive genera- 

 tions there should occur individual variations useful to 

 Nature's wild species as being capable of modifying 

 and developing them ; but between this probability 

 and the fact that man, in forming his breeds of 

 domesticated animals, finds certain individual variations 



